This revised application proposes to complete the follow-up of the classic Vietnam Drug Users Study. The original study was conducted in 1972 and 1974 by the Washington University School of Medicine to assess the extent of drug and other substance abuse and adjustment problems to civilian life of Vietnam War soldiers one year and three years after departure from Vietnam. The value of the study was enriched by inclusion of a civilian comparison sample matched with the general-sample veterans. Phase I, the feasibility study (DA07939-01) is in its 17th month as of October 1994. The cumulative mortality rates of subjects now reaching their mid-40s on average currently stand at 13.5% for oversampled veterans who tested positive for urinalysis, at the time of departure from Vietnam, 5.3% for drug-negative general-sample veterans, and 1.4% among the comparison sample. Among VA medical utilizers, 46.2% of hospitalizations and 24.4% of outpatient visits were treated by substance abuse or psychiatric specialists. Phase II, the instrumentation phase (DA07939-03) has just been funded for the period of October 1994 to July 1995. Phase III, the main study and the current application, requests funds for three years (July 1995 to June 1998) to conduct in-person interviews with the respondents selected from the pool of 1,099 known alive and who were interviewed at least once in the original study. Data collection and analysis aims are as follows: 1) To complete in-person interviews with a minimum of 830 original study respondents. 2) To collect hair samples from all interviewed respondents who consent to hair sampling. 3) To update VA medical records to include utilization information for 1993 and 1994. 4) To compare the prevalence rates of substance use and abuse, psychiatric problems and other outcomes by 4a) sample and urinalysis status at departure and 4b) by risk status categories derived from hypotheses implicit in the original study results. 5) To chart patterns of substance use over the period encompassing pre-Vietnam to present, including: 5a) frequencies and quantities; 5b) abuse and dependence; 5c) transition patterns across routes of administration; and 5d) transition patterns across classes of drugs. 6) To test associations of hypothesized stage- specific risk factors with the course of drug use over adult years based on a normative and maladaptive life course perspective and on findings from existing Vietnam veteran studies and general-population and clinical population follow-ups. 7) To test causal relationships of the major constructs and substance use and other behavioral indicators based on the causal models developed for PTSD, criminal desistance, health care utilization and physical health consequences. 8) To validate self-reported use of cocaine, opiates and methamphetamine by hair drug testing among an estimated 340 veterans and nonveterans at risk for current use based on the original study. 9) To cross-examine self-reported use of VA medical care since 1974 with VA medical records among an estimated 290 living VA medical care utilizers.